Tinted contact lenses have gained greater popularity as a result of the rise in the general acceptance of contact lens, greater public sensitivity to personal appearance and improved contact lens structures (hard lenses vs. soft lenses vs. oxygen permeable lenses, etc.). A variety of manufacturing techniques have been described for generating tinted contact lenses.
Colored contact lenses can be of two general categories. The first being contact lenses which use essentially transparent enhancement colors and allow the color of the natural iris to show through but combine with that natural color to produce a new appearance. Such tinted lenses might typically be used to turn a hazel eye to an aqua colored eye. This class of colored lenses may not be able to change an underlying dark colored, brown iris to blue. The second category is the opaque class of tinted lenses in which the color masks the natural iris color and presents a new color on the outside of the eye. This class of lenses is able to render a brown eye blue.
Various methods have been employed to produce lenses in these two classifications. They differ in a number of ways, but primarily so in the selection of opacifying or non-opacifying media as part of the coloration of the lens. The use of an opacifying media blocks the appearance of the iris from showing through the lens unless the coverage of the media over the iris portion of the lens is less than complete. The texture of the coverage of the opacifying media on or in the lens will be a significant factor in the cosmetic quality of the lens.
Wichterle, U.S. Pat. No. 3,476,499, patented Nov. 4, 1969, describes that--
"It has also been attempted selectively to color hydrogel contact lenses by surface printing. An imprint on the exposed outer surface of the lens is unacceptable for reasons of appearance and it is very difficult to produce an imprint on the inner or contact surface of the lens which does not unfavorably affect the smooth surface finish necessary for avoiding irritation of the cornea." PA0 "Thus, it is possible without difficulty to prepare lenses with, e.g., colored central portions and clear edges, or with an annular colored portion corresponding to the iris." PA0 "When it is desired to apply the dye to one surface only, or to specific portion of the surface, the prepared lens may be placed on a fixture or in a mold, and the reactive dyestuff formulation applied only to a specific portion or portions of the lens surface." PA0 "By the first method, the tinted button is polymerized first, placed in a mold and a hydrogel co-monomer mixture is poured around the periphery of the tinted button and polymerized. The second method is to polymerize the clear button initially and form a centrally positioned aperture through this clear button. The co-monomer mixture including the dye is then poured within this aperture and polymerized." PA0 "A third method for forming the clear and tinted button combination is to form either a tinted or clear button of the normal soft contact lens blank size, slice this button in half and polymerize a co-monomer mixture of the opposite type, i.e., tinted or clear, onto the originally formed button thereby forming a `double layer` button with the lower portion of the button being tinted or clear and the upper portion being the opposite. In the cutting step the colored portion should be on the bottom so that the depth of cut used in forming the base curve will determine the diameter of the tinted area." PA0 "forming first a thin covering layer of the hydrophylic polymer on a regular surface of a smooth pad, e.g. on a polished glass plate. Such plan-parallel very thin layer may be easily made by putting a drop of the initiated monomer mixture onto the pad and covering it with a smooth covering plate, e.g. a thin glass plate such as used for covering specimen for microscopical examination. Air bubbles are to be avoided. As soon as the access of the oxygen is excluded, the polymerization takes place rapidly. The covering plate is removed, if necessary after swelling the polymer in water or alcohol. The polymer layer dries rapidly when exposed to the atmosphere. Now, the colored pattern can be drawn in front view onto a planar surface so that the drawing and/or dyeing is very convenient and reliable. The pattern or a part of it may by also printed using a stamp or other printing die or stencil. Alternatively, a ready made pattern on a thin foil, e.g. a color film copy, may be laid onto the first polymer layer. Thereafter another drop of the initiated monomer mixture is put onto the pattern and covering layer, and a finished hydrogel contact lens or the front part of the artificial eye is pressed slightly thereon until the whole is firmly bound by the polymerized monomer mixture which has party penetrated into the two hydrogel layers. The procedure is made easier if the hydrogel lens or the front part of the artificial eye is first polymerized under at least partial dehydration, the lens or similar being pressed onto a smooth glass or metal surface heated above about 100 degrees C. The dehydrated polymer becomes soft and plastic at about 120 degrees C., but any amount of water contained therein decreases the softening temperature. The lens and the pad are then cooled down under the softening temperature so that the lens, after having been removed from the pad, is now planarized. It can be easily bonded to the covering layer with the colored pattern by a single drop of initiated monomer mixture. Finally, the whole is swelled, advantageously in water or in a physiologic solution, whereby the lens or the front part of the artificial eye returns to its original shape. The change of curvature caused by the thin covering layer and pattern is in most cases negligible. If necessary, the original lens may be a little more curved so that the change shifts the curvature to the desired optimum." PA0 "Swollen contact lenses or eye protheses from such hydrogels can easily be coloured for instance with reactive dyes which become bonded the hydroxyl groups, or with other soluble or insoluble dyes, or possibly pigments, which can be mixed into a monomeric mixture before polymerization (Czechoslovak Patent No. 116,900). Soluble dyes easily pass into the eye so that it is as a rule more convenient to use insoluble dyes and especially covering pigments. However, pigments in a poorly viscous monomeric mixture before the beginning of polymerization easily sediment, especially in a rotating mould, and appear then on the outer surface of the lens. This is undesirable because every pigment would have to be subjected to may years testing for physiological harmlessness, and also for aesthetic reasons because a lens or prosthesis coloured on the surface with a covering dye or pigment lacks the natural lustre of the eye in which the coloured layer of the iris is located below the transparent cornea [sic]. In order to comply with hygienic and aesthetic requirements it is most suitable to have when the coloured layer located inside the lens in order that it may not come into contact with the living tissue and be covered with a transparent hydrogel layer."
Consequently, the patentee employs rotational molding to cause a precipitated light absorbing material in the polymerizable mixture to be distributed to an annular zone about the vision region of the lens.
According to Foley, U.S. Pat. No. 4,252,421, patented Feb. 24, 1981: "One prior art method is to paint or print a colored central portion onto a soft contact lens using an implement such as a brush." Another technique involves "a chemical printing process for coloring soft contact lenses." Foley "several problems with the printing type of technique." . They are: "the color is only printed on the lens after it has been manufactured and, therefore, is not uniformly dispersed through the lens material itself." "Water soluble dyes have also been used to provide the tinting." Foley employs a water soluble dye to tint that are polymer bound to the backbone of the polymerized co-monomer mixture used to make the lens. In this respect, reference is made to Su, U.S. Pat. No. 4,468,229, patented Aug. 28, 1984, for another disclosure on the use of polymer bound dyes. According to Su, col. 7, lines 34-37:
Su further states, at col. 7, lines 50-58:
Foley, at col. 10, lines 51-60, describes two molding methods for making a tinted lens, and at col. 11, lines 24-33, a third method, which are discussed as follows:
Wichterle, U.S. Pat. No. 3,679,504, patented July 25, 1972, describes a number of techniques for making a colored molded contact lens. One technique, shown in French Patent No. 1,499,774, casts a polymer layer of the lens on a rotating mold, a very thin layer of opaque matter is deposited on the exposed polymer face (layer) and covered with a second layer of the monomer mixture, which is then polymerized under rotation to form the finished lens. The opaque material may simulate the iris, pupil, and/or the sclera of an eye. Another technique involves
Wichterle, Canadian Patent No. 815,956, issued June 24, 1969, also describes techniques for making colored molded lens. At page 1, the patentee describes
Canadian Patent 815,956, thereafter describes a method for making a molded colored lens which appears to be the same represented for French Patent No. 1,499,774, supra.
LeGrand, et al., U.S. Pat. No. 3,712,718, patented Jan. 23, 1973, describes a procedure of making a colored lens by cutting into an already shaped lens and filling the cut with the coloring material.
Neefe, U.S. Pat. No. 4,472,327, patented Sept. 18, 1984, describes embedding light reflecting particles, such as mica or finely ground oyster shells, in the lens during molding.
Knapp, U.S. Pat. No. 4,582,402, patented Apr. 15, 1986, and U.S. Pat. No. 4,704,017, patented Nov. 3, 1987, describe the deposition of colored dots on the surface of a contact lens in the iris area. The patents use conventional printing with a soft pad which picks up the pattern from an etched plate and deposits the dot pattern onto the surface of the lens.
The process of this invention lends itself to the more difficult manufacturing challenge associated with the manufacture of opaque tinted lenses. This process is not limited to opaque tinted lens and can be readily employed to produce the enhancement tinted products. The tinted lenses and methods for producing same, which are the subject of this invention, shall be seen to be of uncompromised quality and capable to being mass produced at very low cost.